ABSTRACT Stingless bees (Apoidea) are widely distributed and commercially cultivated in artificial hives in fruit gardens. Their propolis are commonly used in traditional medicine to treat various diseases (e.g., abscesses, inflammations, and toothaches) and as a constituent of numerous health products. Thus, this study aimed to (i) develop and validate a high-performance thin layer chromatography method for the quantitation of major active constituents (α- and γ-mangostins) in propolis produced by five stingless bee species (Tetragonula fuscobalteata Cameron, T. laeviceps Smith, T. pagdeni Schwarz, Lepidotrigona terminata Smith, and L. ventralis Smith) cultivated in Thai mangosteen orchards and (ii) determine an optimal extraction solvent. Separation was performed on a silica gel 60 F254 plate using toluene/ethyl acetate/formic acid (8:2:0.1, v/v/v) as a mobile phase, and the developed method was validated to assure its linearity, precision, accuracy, and limits of detection/quantitation. Propolis extract from T. fuscobalteata exhibited the highest mangostin content, and acetone was shown to be more a more effective extraction solvent than dichloromethane, ethanol, or methanol. Thus, the simplicity and reliability of the developed method make it well suited for the routine analysis (e.g., for quality control) of commercial products containing stingless bee propolis.

ABSTRACT Pluchea indica (L.) Less., Asteraceae, is a medicinal plant which contains a high amount of phenolic compounds such as caffeoylquinic acid derivatives. The leaves have been traditionally used as a nerve tonic and extensively as herbal tea. This study aimed to develop and validate an HPLC method to quantitatively analyze six caffeoylquinic acid derivatives, viz. 3-O-caffeoylquinic acid, 4-O-caffeoylquinic acid, 5-O caffeoylquinic acid, 3,4-O-dicaffeoylquinic acid, 3,5-O-dicaffeoylquinic acid, and 4,5-O-dicaffeoylquinic acid in P. indica leaf extract. HPLC was carried out in a Hypersil BDS C18-column eluted with 0.5% acetic acid in water and methanol using gradient elution with a flow rate of 1 ml/min and detection at 326 nm. The method validation was performed to assure its linearity, precision, accuracy and limits of detection and quantitation. Several extraction techniques including maceration, decoction, digestion, Soxhlet extraction, and ultrasound extraction, were used to extract active constituents. The ultrasound extraction with 50% ethanol yielded the highest concentration of these caffeoylquinic acid derivatives in the P. indica leaf extract. Our developed HPLC method is simple and reliable for a routine analysis of the six caffeoylquinic acids in P. indica leaves and could potentially be applied to be used in commercial herbal products.